Bimetallic billet and preparation and rolling thereof



Oct. 2, 1945. 2,386,091

BIMETALLIC'BILLET AND PREPARATION AND ROLLING THEREOF W. A. CARLSONFiled April 23. I942 I I INVENTOR VVEZZzamA. Carl-sun dinalextensib'ilities upon rolling of the bimetallic Patented Oct. 2, 1945UNITED STATES PATENT OFFlCE BIMETALLIC BILLET AND PREPARATIONAND'ROLLING THEREOF corporation of Virginia William A. Carlson,Pittsburgh, Pa., assignor to Superior Steel Corporation, Pittsburgh,Pa., a

Application April 23, 1942, Serial No. 440,155

7 Claims. (01. 29-188) making and rolling of bimetallic billets made upof a component of steel and one or more components of relatively softmetal which has a relativelyv great longitudinal extensibility uponrolling of the bimetallic billet.

Consider, for example, the'rolling of a bimetallic billet having abacking member of steel and a facing member or membersof gilding metal.When such a bimetallic billet is heated and hot rolled the gilding metalis extended longitudinally. J during the hot rolling to a greater extentthan the steel. If. the steel and gilding metal components are the samelength when the billet is formed the gilding metal will roll out togreater length in the hot rolled strip than the steel and thusconsiderable gilding metal will be wasted. If, on the other hand, thegilding metal is made shorter than the steel when the billet is formeda. portion of the steel is left exposed and during hot rolling thegilding metal is rolled out over such portion. A satisfactory bondbetween the steel and gilding etal over the originally exposed portionof e. steel is not assured because" of the formatio C of oxide or scaleupon such portion of the steel upon heating and hot rolling the billet.The scale may prevent the formation of a satisfactory bond between thegilding metal and th steel with the result that the components mayseparate in the finished strip when subjected to die forming or otheroperations.

I have discovered how to avoid undue wastage of gilding metal orwhatever relatively soft metal is used s a component of a bimetallicbillet with- I out the, disadvantage of the formation .of oxide 5 Yferred methods of practicing the same proceeds.

or scale upon an originally exposed portion of the steel or otherrelatively less extensible component. I make a bimetallic billet byforming components of metals having different longitubillet with thecomponent having the greater longitudinal extensibility shorter thanthat havsemble the components and I provide for protecting againstoxidation a portion of the longer component not originally covered bythe shorter component so that when the billet is heated and rolled theoriginally shorter but relatively extensible'component will flow out andcover such protected portion of t e originally longer component,

the two compone' ts in the finished strip being 7 of approximately thesame length.

The pr tection of the originally uncovered portion 0 the longerbillet'component may be accomplished in various ways. I prefer to coverthe;surface portion of such component which is in generally longitudinalalignment with the shorter component so that such surface portion doesnot substantially oxidize during heating and hot rolling and so that theoriginally shorter component may flow out over the protected portion ofthe originally longer component and form a tight bond therewith. Ipreferably place protecting means over the originally uncovered portionof the l0nger billet component, which protecting means may be displacedby the originally shorter component during rolling. For example, I mayemploy a slug or small plate of steel or other metal as theprotectingmeans or device and fasten it over the portion of the surfaceof the originally longer billet component which is in generallylongitudinal alignment with the originally shorter component When thebimetallic billet is heated and rolled the originally 4/ longercomponent which was originally covered by the slug or plate so that asatisfactory tight bond in the finished strip between the respectivecomponents may be obtained. Preferably the protective device is made ofrelatively inexpensive metal such as ordinary steel so that its loss inthe finished strip is not economically serious.

Other details, objects and advantages of the invention will becomeapparent as the following description of certain present preferredembodiments of the invention and certain present prec'ertain presentpreferred embodimentsoi the in I of practicing the same, in which IFigure l is a perspective view of a bimetallic billet with a portion cutaway; J I

Figure 2 is a central vertical longitudinal crosssectional perspectiveview of the billet shown in Figure 1. also with a portion cut away;

Figure 3 is a view similar to Figure 2 showing a modified structure; and

Figure 4 is a view similar to Figures 2 and 3 showing a further modifiedstructure.

Referring now more particularly to the drawing, there is shown inFigures 1 and 2 a bimetallic billet comprising a steel backing member 2and gilding metal facing members I and 4 assembled with and lyingagainst the backing member at its top and bottom, respectively. Thebacking member is provided with four projecting flanges I whichinitially provide with the intermediate surfaces of the backing. memberchannels in which the facing members 3 are disposed, after which theflanges are peined over against the edges of the facing members to holdthe billet components in assembled relationship so that the compositebillet may be heated and hot rolled.

As shown, the facing members are preferably relatively thin as comparedwith the backing member. Each of them is also made materially shorterthan the backing member. This is done because the relatively softmaterial of the facing members has relatively great longitudinalextensibility in rolling of the bimetallic billet, that is, when thebillet is heated and hot rolled the facing members roll out to greaterlength per unit of original length than the backing member. The facingmembers are preferably made Just enough shorter than the backing memberthat during rolling the facing members and the backing member will beelongated to approximately the same length, thus avoiding substantialwastage of material. While I am not certain, I believe that the relativelongitudinal extensibility between the facing and backing members occursprior to bonding of such members together and that after they havebonded together due to the pressure applied to them in the rolling millafter they have first been raised to welding heat there will be littleif any relative longitudinal extensibility. Experience readily shows howmuch shorter than the backing member the facing members should be forany given combination of backing and. facing members. I have found thatwhen backing and facing members of approximately the shape andproportions indicated in the drawings are employed the facing membersshould be ordinari y from two to three inches shorter than the backingmember when the length of the billet is of the order of five feet andwhen the backing member is of ordinary carbon steel and the facingmembers are of gilding metal (in the neighborhood of 90% copper and inthe neighborhood of zinc).

In order to cover and protectthe surface portions of the backing memberwhich lie generally in longitudinal alignment with the facing membersbut are not originally covered by the facing members I provide slugs orplates 8 as shown which are preferably of the same width as the facingmembers and which abut the respective facing members end to end as shownin Figure 2 and whose length is such that the total of the length ofeach facing member and the abutting slug is substantially equal to thelength of the backing member. The slugs are preferably made of metal,any relatively cheap metal ordinarily satisfactorily serving thepurpose. I prefer to make the slugs of ordinary carbon steel and theymay be made of steel identical or substantially identical to that usedfor making the backing member 2. The thickness of the slugs is notimportant except that they should be thick enough to serve their purposeand to protect the underlying surface portions of the backing memberuntil the facing members are elongated during rolling to cover suchportions. It is convenient to make the slugs of the same thickness asthe facing membersand they are thus shown in the drawings.

A above stated, the facing members are applied to the backing memberbetween opposed flanges i whereafter the flanges are peined in againstthe edges of the facing members to maintain the assembly. I find itdesirable to also position the slugs against the backing member and inend to end abutting relationship with the fac ing members at the sametime as the facing members are applied and to pein over the flangesagainst the facing members and the slugs in the same operation. Sincethe slugs are not intended to form a permanent part of the billet or ofthe strip to be rolled therefrom it is not essential that they be heldas firmly as the facing members, although the slugs should be heldagainst the surface portions of the backing member which they cover insuch a way as effectively to exclude air from such surface portionsduring heating of the billet prior to hot rolling. and during theinitial stages of hot rolling and until the facing members are elongatedto cover the thus protected surface portions.

When the billet has been heated and is passed through the hot rollingmill the facing members are longitudinally extended to a greater degreethan the backing member and, as above indicated, the original lengths ofthe facing and backing members are determined so that at the end of therolling they will be of substantially the same length. When the facingmembers begin to elongate relatively to the backing member they displaceor push the slugs ahead of them and the slugs ultimately leave thebillet and drop down onto the floor. Due to the shortness of the slugsin the longitudinal direction there is relatively little frictionholding them in place and hence they are subject to ready displacementby the facing members when the latter diflerentially elongate relativelyto the backing member.

The positioning of the slugs on the billet depends upon the type ofrolling mill used and the manner of rolling. In some hot rolling millsthe opposed rolls do not in all passes rotate at such speed that theperipheral speeds of the opposed roll surfaces engaging the work areequal. Sometimes the work is passed back and forth between rolls so thatthe forward end of the work in the first pass is the trailing end in thesecond pass. Depending upon the conditions of rolling it may bedesirable to provide the slugs 6 at opposite ends of the billet as shownin Figure 2. This is done when the tendency of the rolls during hotrolling is to elongate one of the facing members in one directionrelatively to the backing member and the other facing member in theopposite direction relatively to the backing member. The conditionsdetermining the position of the slugs is readily determinable by thoseskilled in the art for any given mill and rolling procedure.

Figure 3 shows a modified form of structure which is identical with thatshown in Figures 1 and 2 except that both slugs are at the same end ofthe billet. In Figure 3 parts corresponding to the parts shown inFigures 1 and 2 are identified with the same reference numerals eachwith a prime affixed. A billet of the type shown aaeaoai in Figure 3wouldbe used when the upper and lower rolls in the hot mill rotate atsuch speeds that the opposed roll surfaces engaging the work operate atthe same peripheral velocity and when the tendency is to elongate bothfacing members in the same direction relatively to the backing memberFigure! shows in which parts corresponding to the parts shown in Figures1, 2 and 3 are identified by the same reference numerals 'each with adouble prime amxed. In Figure 4 a, slug 6" is employed only on the topof the billet, the lower facing member 4" being of the same length asthe backing membar 2'. Such a structure may be employed, for

example, when dissimilar facing members are used. The facing member 4"may be of a metal having a longitudinal extensibility substantially thesame as that of the metal of the backing member 2". For example, abimetallic billet having a. backing member of ordinary steel and afacing member of stainless steel may have both of such members ofsubstantially the same length as they will elongate to approximately thesame extent when the bimetallic billet is hot rolled. The billet shownin Figure 4 may have the backing member 2' of ordinary steel, the facingmember 3" of gliding metal, the facing member 4" a further modifiedstructure" of stainless steel and the slug 8" of any readily length ofsuch members and consequently also in the length of the slugs.

The slugs when applied should be pressed firmly against the ends of thefacing members with which they respectively cooperate. The slugs willordinarily be sheared from bars and I find that the shear fins on theslugs are useful as providing mean tending to embed themselves to someextent in the ends of the facing members, thus forming a suflicientlyairtight seal at the junction between each facing member and itsadjacent slug. If desired the slug maybe struck toward the cooperatingfacing member with a hammer or other tool when applied. If a slug shouldslip during peining of the flange of the backing member against theedges of the facing members and slugs it can ordinarily bedriven backinto proper position even after peining.

While I have shown and described certain present preferred embodimentsof the invention and certain present preferred methods of practicing thesame, it is to be distinctly understood that the invention is notlimited thereto but may beotherwise variously embodied and practicedwithin the scope of the following claims.

I claim:

1. A method of preparing and rolling a bimetallic billet comprisingforming billet components having different longitudinal extensibilitiesupon rolling of the blmetallc bllet so that a component having arelatively great longitudinal extensibilit5 is shorter than a componenthaving a relatively small longitudinal extensibility, assembling saidcomponents so that the first mentioned component covers only a portionof an opposed face of thesecond mentioned component. leaving another ofsaid face to protect the same against oxidation, heating the bimetallicbillet formed by assembly of said components and rolling the heatedbillet so that the first mentioned component is longitudinally extendedrelatively to thesecond mentioned component to cover said originallyexposed portion of said face thereof. 5

2. A method of preparing and rolling a. bimetallic billet comprisingforming billetcomponents having different longitudinal extensibilitiesupon rolling of the bimetallic billet so that a component having arelatively great longitudinal extensibility is shorter in the directionof rolling than a component having a relativelysmall longitudinalextensibility, assembling said components, fastening over a portion ofthe second mentioned component not covered by the first mentionedcomponent upon assembly of the components a protective device to protectsuch portion against oxidation, heating the bimetallic billet formed byassembly of said components and rolling the heated billet so that thefirst mentioned component is longitudinally extended relatively to thesecond mentioned component to displace and separate from the billet saidprotective device and cover said portion of the second mentionedcomponent.

3. A method of preparing and rolling a bimetallic billet comprisingforming a billet component relatively long in the direction of rollingand a billet component relatively short in the direction of rolling ofmetal having a greater longitudinal extensibility upon rolling of thebimetallic billet than the metal of the relatively long component,assembling said components and deforming at least one thereof whereby tohold them together, fastening over a portion of the first mentionedcomponent not covered by the second mentioned component upon assembly ofthe components a protective device to protect such portion againstoxidation, heating the bimetallic billet formed by assembling of saidcomponents and rolling the heated billet so that the second mentionedcomponent is longitudinally extended relatively to the first mentionedcomponent to displace said protective device and cover said portion ofthe first mentioned component. i

4. A method of preparing and rolling a bimetallic billet comprisingforming a flanged backing member relatively long in the direction ofrolling and a facing member relatively short in the direction of rollingofmetal having a greater longttudinal extensibility upon rolling of theblmetallic billet than the metal of the backing member, assembling thebacking and facing members and deforming flange means of thebacking-member to hold the facing member thereto, positioning over a".portion of the backing member not covered by the facing member uponassembly of the members a protective device to protect such portionagainst oxidation, holding the protective device in place by flangemeans of the backing member, heating the thus assembled members androlling the same so that the facing member is longitudinally extendedrelatively to the backing member to cover said portion of the backinmember.

or metal having relatively great longitudinal extensibillty upon rollingof the bimetallic billet. said components being held together. and ametal protective device separate from the second mentioned componentdisposed in longitudinal hlignment with the second mentioned componentconnected with the first mentioned component and covering a portionthereof not covered by the second mentioned component upon assembly ofthe components to protect such portion against oxidation.

6. A bimetallic billet comprising a flanged steel backing member and afacing member or relative-! 1! soft metal and oi less thickness andshorter than the backing member lying against the backing member andheld thereto by flange means of the backing member and a metalprotective device separate from the facing member disposed inlongitudinal alignment with the facing member and also held to thebacking member by said flange means and covering a portion oi thebacking member not covered by the facing member upon assembly of themembers to protectgsuch portion gainst oxidation. I

7. A bimetallic billet comprising a flanged steel backing member andopposed lacing members of gliding metal of less thickness than thebacking member lying against opposed faces 0! the backing member andheld thereto by flange means of the backing member. at least one or thefacing members being shorter than the backing member. and a metalprotective device disposed in iongitudinal alignment with a lacingmember which is shorter than the backing member, said metal protectivedevice being separate from such facing member and held to the backingmember by at least certain 0! said flange means and covering a portionof the backing member not covered by such facing member upon assembly ofthe members to protect such portion against oxidation.

WILLIAM A. CARLSON.

